1. Field of the Invention
The present invention relates to a printing apparatus to be shared between a plurality of users, and more particularly to a printing apparatus having a confidential print function of holding print jobs designated in advance until password entry.
2. Description of the Related Art
Printing apparatuses shared between a plurality of users produce printed outputs as required. This involves a problem that printed matters to be kept secret can possibly be exposed to other users.
To overcome this problem, Japanese Patent Laid-Open Publication No.Hei 8-244315 discloses a technology as to an image forming apparatus and method that comprise a print function in which a user sends password-protected print data to the printing apparatus in advance, and the printing apparatus holds the print data so that the printing is not started until the user who has requested the printing actually operates the printing apparatus to enter the password. Hereinafter, this function will be referred to as confidential print function, since the printed output cannot be obtained unless the user by himself/herself enters the password.
In the above-described image forming apparatus, however, if normal printing is performed when the user comes to the printer location to enter a command for starting the confidential print (secret print) into the image forming apparatus, there arises a waiting time.
Accordingly, Japanese Patent Laid-Open Publication No.Hei 11-91210 discloses, against the above-mentioned problem, a technology as to a printer system which suspends normal printing so as to print secret data preferentially.
For another method of outputting printer-input data in sequence yet outputting data of urgent necessity in preference to the other data, Japanese Patent Laid-Open Publication No.Hei 5-189174 discloses a technology as to a method of controlling a plurality of print queues in which a plurality of print queues allocated to individual print modes produce printed outputs in accordance with the priority attributes and the order of input.
The printer system disclosed in Japanese Patent Laid-Open Publication No.Hei 11-91210 described above gives higher priority to the secret data print, thereby reducing the users' waiting time in printing secret data. Nevertheless, if a plurality of users successively instruct secret data print from their PCs, a plurality of pieces of secret data are output in succession. This requires the prevention of a mix-up between the printed outputs. Moreover, the plurality of users come to the printer location to fetch their printed outputs, increasing the possibility of exposure of the printed outputs to other users.
On the other hand, the method of controlling a plurality of print queues disclosed in Japanese Patent Laid-Open Publication No.Hei 5-189174 is to execute print jobs in order of acceptance of the print requests. Therefore, entering a plurality of pieces of privilege attribute data can possibly preclude outputs in the user-expected order.
For example, if privilege attribute data is entered during the execution of a print job, this print job is completed before a print job corresponding to the privilege attribute data is executed. Then, print jobs for normal data follow in order of acceptance of their print requests. Accordingly, the print jobs previously input as normal data, though their earlier outputs are desired, sometimes output after the print job for privilege attribute data does.